Tag Archives: AR5

The destruction by ISIS (Islamic State) of the ancient Assyrian city of Nimrud in Iraq and potential destruction of Palmyra in Syria has shocked the world—almost as much as the organisation’s previous beheadings of its captives.

Unfortunately, an article in this week’s New Scientist on sea level rise titled “Five Metres and Counting” (apologies print or paywall access only) suggests that climate change has already committed the world to the destruction of human heritage many orders of magnitude greater than anything ISIS is capable of doing.

You may be familiar with the Intergovernmental Panel on Climate Change (IPCC)‘s end of century sea level rise forecast (here, page 11 in the report). This pegs the upper sea level rise outcome at just below one metre (click for larger image).

What is less well-known is that this is just the preliminary phase of sea level rise. Given the extent of warming to date plus the warming guaranteed by current levels of carbon dioxide in the atmosphere, we are committed to barrel through one metre. In the words of Michael Le Page from The New Scientist:

Whatever we do now, the seas will rise by at least 5 metres. Most of Florida and many other low-lying areas and cities around the world are doomed to go under. If that weren’t bad enough, without drastic cuts in global greenhouse gas emissions–more drastic than any being discussed ahead of the critical climate meeting in Paris later this year—a rise of 20 metres will soon be unavoidable.

The arithmetic is pretty depressing (chart from New Scientist article): 0.4 metres for mountain glaciers, plus 0.8 metres for ocean thermal expansion, plus 3.5 metres for the West Antarctic ice sheet (the areas in orange in the chart below, click for larger image). If we go past 2 degrees Celsius of warming and get to 4 degrees, then we add all the blue bars as well.

Since the IPCC’s Fifth Assessment Report (AR5) was published, fresh evidence has emerged relating to West Antarctic ice sheet instability. Moreover, two large basins, the Aurora and the Wilkes, that form part of the East Antarctic ice sheet also appear vulnerable. In short, if we push up to 4 degrees Celsius of warming, then we are likely committing ourselves to 20 metre sea level rise.

So we’ve seen what ISIS had done in Nimrud, this is what we will do to Venice with 20 metres of sea level rise (source: here):

And New York:

These projections are Old Testament in terms of the scale of the catastrophes they portend; indeed, ISIS could only dream of unleashing such wanton destruction. Yet, in our failure to tackle climate change, such wanton destruction appears to have been accepted by the G20 elites and, frankly, ourselves.

Addendum:

Had a request for the background papers quoted by New Scientist. Most of these are behind paywalls but the authors frequently make pdfs available on their personal web sites or the web sites of their institutions:

Six years ago, the release of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) caused a considerable stir. I suspect that the publication of the Fifth Assessment Report (AR5), with the first instalment coming this week, will be met with a yawn.

What has changed? I would cite four main factors: 1) the Great Recession, 2) the coordinated and well-financed campaign of climate scepticism, 3) the hiatus in temperature rise and, last but not least, 4) climate change fatigue. I further suspect that even if 1) through 3) had not occurred, 4) alone would have been sufficient to break the momentum of any action to mitigate climate change.

So why can’t we keep our concentration in the face of what must be the greatest threat faced by humanity in the last 10,000 years? Perhaps because the lag between cause and effect, which in the case of climate change is measured in decades rather than years, is just too big.

In the past, I believed that life insurance offered some hope as a role model for evaluating long-horizon risks since the industry is built on individuals evaluating outcomes decades into the future. But in the case of life insurance, individuals can take a rough stab at the distribution of future risk by looking at the distribution of current risk.

A twenty-something woman with young children knows that there is an outside chance that she (or her partner) could die due to a heart attack, stroke or cancer in her thirties or forties. Why? Because out of the few hundred friends and acquaintances that she has come into contact with over the years, she probably knows, either directly or indirectly, more than one person who has died young. In short, life insurance mells well with an individual’s personal life narrative.

But climate change doesn’t. The risk is abstract to the extent that it has no connection with the life experience of most people. Even the burning embers diagram of the Third Assessment Report (TAR) of 2001 does a poor job of communicating risk (and even this was excluded from AR4 for political reasons as you can read here), since it is just a representation of broad categories of risk and not based on experiences that individuals can internalise:

Therefore, while the decadal unit of measurement is most appropriate for measuring the extent and effects of anthropogenic global warming (AGW), it appears too long for social and political action to coalesce. Yet AGW is moving at lightening speed when compared with natural climate change.

The climate scientist Stefan Rahmstorf, writing in the scientist-led blog Real Climate, highlights a recent paper by Marcott et al in Science that reconstructs the global temperature record back over the last 11,000 years. This period, termed the Holocene, encompasses the years since the last glacial period ended, which is broadly commensurate with the rise of human civilisation.

As you can see, we were merrily moving in slow motion toward a new ice age when we started to burn fossil fuels. Rahmstorf then kindly provides us with a chart that adds the back story of temperature during the last ice age plus the IPCC’s central estimate of temperature out to 2100 based on the most likely fossil fuel emission trajectory. The step change is obvious, but is still not fast enough to impact on the future expectations of voters.

With no urge to mitigate emissions visible within the broader population, we appear to be reduced to praying a) that climate sensitivity to a CO2 will come in at the low end of estimates, and b) that this will give us sufficient time for a backstop non fossil-fuel energy technology to be developed and scaled up before extremely dangerous climate change is locked in.

This is a pure, high-stakes gamble: if we don’t get lucky with sensitivity and technology, we are left with a horrendous pay-off in terms of negative climate change effects. Unfortunately, no means of conveying this threat in a way that meshes with the life narratives of ordinary individuals appears to exist.